The Problem With IMIX

Andre Gironda was kind enough to post a comment regarding IMIX to yesterday's blog post, "The World is Lacking Background Traffic." Basically Andre writes that IMIX might be outdated but it's out there. This was something that I was planning on talking about in the future, but since I got the perfect setup, I'll do it now. I have no issue with IMIX, but I do have an issue with thinking that it can provide you good data for how a device will work, performance wise, in your network. Andre is right, it's a bit outdated, in fact I believe it's 7 years old this month and the NLANR (National Laboratory for Applied Network Research), who provided it, had it's funding dry up 2 years or so ago.

For those that don't know what IMIX is, I will steal from a description I found on CAIDA's site: "IMIX derives from analysis of NLANR traces and is tri-modal (e.g., 58% at 40 bytes, 18% at 576 bytes, and 23% at 1518 bytes)."

So to prove this out - I took a Juniper Networks device that is content-aware and ran three benchmarks. It was fairly easy since this device used to be in my network! The three benchmarks are as follows:

1. Setup a test to run IMIX at 20 megabits (yes, my device is wimpy);
   
2. Setup a test to run BreakingPoint's Application Profile for Enterprise Traffic (using release 1.2);
3. Monitor it via SNMP all day to see when I started dropping traffic (yes I have a 10-megabit pipe to the Internet);

(It should be noted that I knew the device couldn't handle our 10-megabit pipe to the Internet, I know this because we had to upgrade it to a larger device after we changed from a T1 to a 10-megabit pipe).  Here's a graph showing the results:

As you see, the IMIX told us the device could perform 18.9 megabits per second without packet loss. The Enterprise Application Profile clocked it at 4.6 and the Actual was fluxing between 4.7 and 4.9.